I'm not sure if the parts will interchange, the numbers are different but the drawings are certainly similar.
F39:
https://www.realoem.com/bmw/enUS/sho...diagId=18_1314
F48:
https://www.realoem.com/bmw/enUS/sho...diagId=18_1169
To me, this isn't a "downpipe" because of the integral configuration of the cat. I guess it's easiest to just call it that, but the part in that thread is "catless", meaning it's a hunk of pipe. I predict you'll have a heck of a time keeping the check-engine light off, and therefore making it really difficult to maintain and even get it inspected. If you learn otherwise, I'm all ears!